This invention relates to a method of exchanging writing implements in a drafting machine between a pen magazine holding a plurality of writing implements and a drawing head, and to an apparatus therefor.
The device disclosed in U.S. Pat. No. 4,288,798 is well known as an exchanging device for writing implements. This exchanging device is constructed in such a way that a plurality of writing implement holders consisting of two elastic clips are disposed in the pen magazine, and a single writing implement holder consisting of two elastic clips is provided in the drawing head. When the writing implements are exchanged, the elastic clips in the pen magazine and the elastic clips in the drawing head are in mutual pressure contact. The device is constructed in such a way that the elastic clips in the drawing head expand the elastic clips in the pen magazine, or the elastic clips in the pen stocker expand the elastic clips in the drawing head.
Accordingly, there is a drawback that the elastic clips constituting the writing implement holder are quickly worn out.
Also, since the device is constructed in such a way that the writing implement holder in the pen magazine and the writing implement holder in the drawing head are identically constructed, the tips of the elastic clips in the drawing head collide with the tips of the elastic clips in the pen magazine when the drawing head approaches the pen magazine for exchange of the writing implements where the writing implements are retained by both the writing implement holders in the pen magazine and the drawing head, and as a result, the elastic clips are broken which is a drawback.
An object of this invention is to eliminate the foregoing drawbacks.